1. Field of the Invention
The present invention relates to a safety back-up sensor, in particular, a sensor with multiple resilient tabs on the shoulder to prevent shifting or rotation of the sensor body, allowing the sensor to be firmly affixed on a vehicle bumper.
2. Description of Related Art
When an ordinary user wants to install a sensor deice in the vehicle, his or her main consideration is the accuracy in detecting the proximity of an object. Elements causing false alarms of the electronic sensor can be either external factors or circuit design problems. The user wants to know whether the sensor device is capable of distinguishing actual objects from noises and accurately approximating the distance between the vehicle and the object, based on the reflection of ultrasonic signals emitted. A primary consideration is whether the sensor is rigidly installed in place so the device can function properly.
With reference to FIG. 5, a conventional back-up sensor device includes a cylindrical body (40), an end plate (43), a rubber bushing (41) and a signal sensor module (42). A hollow core runs through the cylindrical body (40) to accommodate the rubber bushing (41) and the signal sensor module (42). The signal sensor module (42) emits ultrasonic signals through a through hole in the cylindrical body (40) to detect any object within its effective range.
In the conventional method of installing a sensor device, a hole is drilled in the rear bumper of the vehicle, in which the sensor device is installed. When the sensor device is inserted into the bumper, the security of the installation relies on the abrasion force of the external wall of the sensor against the inner wall of the installation hole to grip the device. The external wall of a conventional sensor body (40) usually has a smooth surface. A vehicle riding over bumpy roads is likely to cause rocking, bouncing and vibration of the vehicle chassis and the bumper. Over an extended period of time, the sensor body (40) will likely loosen or become detached from the installation hole.
When assembling the conventional sensor device, the signal sensor module (42) is first inserted into the rubber bushing (41), and the rubber bushing (41) is slid into the body of sensor (40). As such, the sensor body indirectly exerts pressure on the perimeter of the signal sensor module, which may cause dislocation of the sensor leading to aberrations in signal transmission and reception. This phenomenon may well cause false alarms due to incorrect approximation of the distance between an object and the sensor device.
To overcome the shortcoming in the conventional sensor device mentioned above, the present invention provides a type of vehicle back-up sensor, wherein multiple directional and locating constructs are created on the shoulder of the external sensor body to ensure rigid installation of the back-up sensor on the vehicle bumper under all driving conditions.